Refining of mineral oils



Jan. 25, 1944. B. R. s-TRICK A D I 2,339,389

REFINING OF MINERAL O ILS I- iled Dec. 26, 1940 ofmineral oils. ularly concerned with the removal oi. objection- Patented Jan. 25, 1,944

ammo or mean. orLs Barney B. Strickland, Roselle, N. 8.. assignor to Standard Oil Development ration of Delaware Company, a corpoestuaries December 26, 1940, Serial Nb. 371,670

3 Claims.

The present invention relates to the refinin The invention is more particable sulfur-containing compounds and acidic constituents such as mercaptans andthe like irom petroleum oils and is especially concerned 4 occurring acidic oxygen-containing compounds. In accordance with the present process, these constituents are removed from petroleum oils and the quality of the same materially improved by utilizing a reagent selected from the class of alkali metal alcoholates.

with the removal and recovery of naturally- It is known in the art to treat oils, particu- I larly petroleum oils, in order to improve the quality of the same, utilizing numerous solvents and liquid reagents. It is also known in the art to remove mercap'tan compounds and to recover naturally-occurring acidic oxygen-containin compounds such as naturally-occurring high molecular weight petroleum phenols and naphthenic acids. These operations employ various alkali solutions and solid reagents, such as oxides of aluminum, bauxite, silicates, silica gels, and the like.

I have, however, new discovered a process by which the quality of petroleum oil products may be improved and by which constituents which are undesirable in the same may be readily removed and recovered asvaiuable products. In accordance with my process, feed oils containin undesirable constituents, such as suliurcontalning compounds, mercaptans. naturallyoccurring phenols, naphthenic acids .are contacted with an alkali metal alcoholate under conditions adapted to remove the same. i

The process of my invention may be readily understood by reierence to the attached drawing illustrating modifications oi the same. Figure 1 illustrates a solvent treating adaptation and modification of my invention utilizing a solvent comprising a solution of an alcoholate. Figure 2 illustrates a modification of my invenover an alcoholic solution of the alcoholat, while Figure 3 illustrates another adaptation in which the oil being treated is distilled over a solid reagent.

Referring specifically to Figur e 1, it is assumed that the feed oil is a petroleum oil boiling in-the kerosene boiling range and that the reagent methyl alcoholate dissolved in anhydrous methyl zoo-+621) I arrangement of units. In this zone the reactions comprise converting the mercaptans'to mercaptideasthe high molecular weight phenols to phenolates. and the high molecular weight naphthenic acids to naphthenates. Temperature and pressure conditions are adjusted to secure an oil phase and an alcoholic phase containing dissolved therein the mercaptans and acidic oxygen-containing constituents removed from thetreated oil. The treated oil is withdrawn from zone 4 by means of line 5, and further refined or handled in any manner desirable. The alcoholic phase containing the mercaptides, the phenolates, and the naphthenates.: is withdrawn from zone 4 by means of line 6 and passed into Usually it is preferred to recycle at zone I. least a portion of the alcoholic solution until substantiailythe entire quantity of alcoholates "is converted to the corresponding alcohol and salts by means of line 22. In Zone 1, the alcoholic solution is subjected to temperature and pressure conditions adapted to remove overheadby means of line 8, substantially the entire amount oi" alcohol present. This alcohol may be removed from the system, but it is preferably combined with additional alcoholate and recycled. The ebottoms product, comprising a slurry of alcohol,.mercaptides, phenolates, and

which it is subjected to steam, which is introand naturally-occurring comprises a 15% to 20% solution of sodium alcohol. The feed oil is introduced into the sys-- tem by means of line I while the alcoholic solution of sodium methyl alcoholate is introduced by means or line 2. The mixture is passed through mixing zone 3 and introduced into-zone 4 which may comprise any suitable number and co in this manner, the naphthenicacids separate as duced by means of-line ll. Conditions are adjusted to remove overhead by means oi line l3 the mercaptans regenerated from the corresponding mercaptides, and to remove as a bottom by means of line ll, a caustic solution comprising phenolates and naphthenates. The overhead product removed by means of line i3. comprising mercaptans and steam, is condensed and passed into separation zone 23 in which a layer formation occurs.

The mercaptans are withdrawn by means of line 24 while the water tion when distilling the feed oil to be treated I is removed by means oi line'25. The bottoms.

removed from zone Ill by means of line I4, is introduced into regeneration zone 26 in which phenols are regenerated from the corresponding phenolates. This is preferably secured by contacting the same with carbon dioxide, which is introduced by means of line It." The phenols are separated as a separate layer and are removed by means of line it. The lower layer. comprising naphthenates. is withdrawn by means of line 29 and further acidified under conditions to regenerate naphthenic acids from the'corresponding naphthenates. Thlsis preferably secured by the addition of a stronger acid which is introduced by means of line 21, when operating treated oil. condenser 35 and passed into separation zone a separate layer in zone 20, and are removed by means of line ll, whilethe remaining constituents are removed by means or line 23.

Referring specifically to Figure 2, it is assumed that the feed 011 containing mercaptans, phenols,

-, and naphthenic acids is a petroleum oil boiling in the kerosene boiling range. For purposes of. description, it is also assumed that the treatingreagent is an; essentially saturated solution .33. The treated oil iscondensed and separated from the alcohol by means of line 31. Uncondensed alcohol constituents are removed by means of line 33', and condensed and recycled through the system. The bottomsproduct removed from distillation zone.33, by means of .line 39, is cooled in cooler 40 and mixed with .a

relatively small amount of alcohol which is introduced by means of line 4|. The slurry. comprising a relatively small amount of high-boiling oil constituents. mercaptides, phenolates, naphthenates, and the added alcohol, is introduced into separation zone 42. In separation zone l2 an oil phase separates from the alcoholic solution. and is removed by means of line l3.- The alcoholic solution,

drawn from separation zone H, by means of line 44, and introduced into zone 1 and handled in a manner described with respect to Figure -1, for the separation and segregation of the alcohol, the mercaptans, the phenols, and the'naphthenic acid constituents.

Referring specifically to Figure 3. it is assumed I that the feed oil is similar to that described with respect to Figure 2; The feed oil is introduced into the system by means of line 50' and mixed with a quantity of powdered solid sodium methylate, which is withdrawn from storage zone- 52 and injected into the said oil by means of suitable conveying means 53. The mixture is I comprising sodium mer-. captides. phenolates, and naphthenates, is withrespect to Figure 1, in order to segregate the respective constituents. v

The process of the present invention may be widely varied. Although the process may be employed for the treatment of any petroleum oil containing objectionable mercaptans, petroleum oil phenols, and naphthenic acids, it is particularly applicable in the treatment of petroleum oils boiling in the gas oil and kerosene boiling ranges. The process is especially desirable since it permits the recovery of relatively high boiling petroleum phenols, mercaptans, and naphthenic acids in an emcient and economical manholates and are characterized by having a linkage RO-X, in which R represents an alkyl group and in which X is selected from the class consisting of sodium and potassium. Substances of this classare, for example, sodium methyl alcoholate, sodium ethyl alcoholate, sodium butyl alcoholate,

potassium propyl alcoholate, potassium amyl alcoholate, polysodium glycerolate and the various alkali metal alcoholates of the polyhydroxy alcohols, such as sodium glycolate. The preferred reagentsare the sodium alcoholates of the mono hydroxy alcohols, the constituents of which contain from 1 to 4 carbon atomsto the molecule.

The method of contacting the alcoholate and thepetroleum oil will vary considerably and will 'in general depend upon the particular petroleum oil being treated and the particular alcoholate employed. Usually I prefer to contact the oil with an alcoholic solution of the alcoholate. An-

' other preferred modification is to distill the oil over the reagent in the form of an alcoholic solution or in the form of a powdered solid. If an alcoholic solution be employed I prefer that the alcohol in which the alcoholate is dissolved be the alcohol from which the alcoholate was derived. Thus, for example, if sodium methylate be employed, it is preferred that the alcoholate be dissolved in methanol. If an alcoholic solution be employed, it ispreferred that the concentration be in the general range of from 5 to passed through mixing and heatin zone 54 and introduced into distillation zone 55. Temperature-and pressure conditions are adjusted tolremove overhead by means of line 58' the feed oil free of undesirable constituents. The, overhead stream is condensedin condenser 51 and Passed into distillation drum 5!. Uncondensed gases are removed by means of line 59, while the treated distillate is'removed by means of line 60 and further handled in any manner desirable.

withdrawn by means of line I, while the alcoholicsolution, -'comprising alcohol, mercaptides,

phenolates, and naphthenates, is passed into zone I by means of line 44. This bottoms prod not is handled in a manner as described with tion used may be varied depending upon the stances.

the feed oil.

30%, preferably in the range from 10 to 20%- The operating conditions likewise may be widely modified. Temperature and pressure may vary and will depend upon the particular feed oil being treated, the quantity and character of the phenols, mercaptans, and naphthenic acids present, as well as upon the particular alcoholate or alcoholate solution employed. Temperature and pressure conditions will also depend upon the feed rate' and particlesize of solid alcoholates be used. In general, when extracting the oil with an alcoholic alcoholate solution, it is preferred to employ atmospheric temperatures and pressures although temperatures in the general range of 30 to F. may be employed in specific in- If the feed oil be of a relatively high viscosity, it may be desired to employ heating means or to dilute the oil with an inert dilution solvent, as for example a relatively low boiling petroleum oil. The quantity of alcoholate soluconcentration of the solution and the quantity of mercaptans, phenols, and naphthenic acids in Usually, 2 to 20% of reagent per volume of oil is preferred.

When distilling the feed oil over the alcoholate solid or solution, it is usually desirablea'i operate Letters Patent is as follows:

. should not be construed as limiting the same in any manner whatsoever.

Example 1 A kerosene distillate containing approximately 0.2% phenols by weight was extracted in two stages with 2% by volume ofa 30% solution of sodium methylate in methanol. The following 1. A process for the recovery and segregation ofnaturally-occurring phenols, naphthenic acids data were obtained: a

Color, Phenol S. No.

Untreated kerosene +20 200 Extracted with 2x2% of 30% NaOMe in MeOH +27 1 I Phenol number is expressed as milligrams of 't-arhylphenol per 100 v milliliters of 011.

It is apparent that sodium methylate is effective in removing phenols from feed oils.

Examplez A heavy prime cut naphtha was extracted in Rerun over 1% of 30% NaOMe in MeOH (twice theoretical amount) with a maximum still temperature of 350 F.

0. 344 V: s1. sour.

1 Copper number is ex ressed as milligrams of m t per 100 milliliters of oil. p Heap an sulfur What I claim as new and wish to protect by and mercaptans from petroleum oil, which comprises contacting the oil with an alcoholic solution of an alkali metal alcoholate, separating the mixture into an oil phase and an extract phase containing the dissolved phenols, naphthenic acids and mercaptans, separately removing the oil and extract. phases, distilling off the solvent from the extract phase, diluting the resulting product with water, stripping the aqueous mixture with steam to remove mercaptans, reactin the stripped product with carbon dioxide to liber-' ate phenols which are drawn ofi, and acidifying the residue to separate naphthenic acids.

2. A process for the recovery and segregation of naturally-occurring phenols, naphtlienic acids and mercaptans from petroleum oil, which comprises contacting the oil with an alcoholic solution of an alkali metal alcoholate, distilling ofl the alcohol and oil from the alcoholate, condensing the oil, recycling the alcohol to the contacting step, diluting the still residue with water, stripping the aqueous mixture with steam to remove mercaptans, reacting the stripped product with carbon dioxide to liberate phenols which are drawn oil, and acidifying the residue to separate naphthenic acids.

3. A process for the recovery and segregation I of naturally-occurring phenols, naphthenic acids BARNEY R. S'I'RICKLAND. 

